Identified the gene base of our fingerprints

Pattern formation in their sights: Researchers have discovered which genes control the three main patterns in human fingerprints – arches, vortices or loops. According to this, there are 43 gene locations that are involved in the development of these groove patterns on our fingertips. Contrary to what was thought, many of these genes are not responsible for skin structure, but for limb development. That explains why the finger patterns are closely related to the hand proportions.

Our fingerprints are unique in several ways. Because the structure of our fingertips formed from grooves and depressions is found predominantly in primates in the animal kingdom and is individually different. There are three basic types – arches, loops and swirls, but the individual characteristics of these main patterns are different for each person. This is one of the reasons why fingerprints are used in criminology, but also in technology for identification.

The three main patterns of human fingerprints. © Fudi Wang

Looking for the genetic basis of pattern formation

But how does the unique pattern of the fingerprints come about? It is clear that the individual shapes of the fingerprints are created in the womb. From around the third month of pregnancy it is clear whether the grooves on a finger of the fetus form loops, vertebrae or arches. “But the mechanisms behind their formation and variation were largely unknown up to now,” explain Jinxi Li from Fudan University and his colleagues.

In search of the defining genes for our fingerprints, the research team carried out genome-wide comparative analyzes for a total of 23,000 people from different population groups worldwide. In doing so, they looked for gene locations for which a connection to one of the three main patterns of the finger structures could be established.

Interaction of 43 genes

The team actually found what they were looking for: In the genome of Han Chinese, they identified a total of 43 loci that are closely related to the fingerprint pattern in people of different origins. Twelve of these gene variants can be assigned to the so-called pattern block – the mostly very similar prints of the middle three fingers. “For the first time, this provides a genetic basis for these long-known correlations,” said Li and his colleagues.

The large number of genes involved also confirms that the human fingerprint is based on a complex interaction of many genetic factors. Each individual gene has only a minor influence; the individual pattern is only created in combination. “It is therefore not possible on the basis of these findings to predict the individual fingerprint pattern based on a person’s genotype alone,” emphasize the scientists.

Relation to the growth of the limbs

However, the three main patterns of the prints – vertebrae, loops or arches – can certainly be assigned to certain gene variants, as Li and his team report. They were able to prove this experimentally for one of the genes, EVI1: if you changed this gene in mice, the shape of their skin grooves also changed. In humans, the EVI1 gene is active in the tips of the fingers and toes in the early embryonic stage, where it influences the connective tissue cushions that shape the later shape of the skin grooves.

Surprisingly, it was previously assumed that genes for the skin structure in particular control the formation of fingerprints. But EVI1 and most of the other genes now identified are involved in a far more fundamental process: limb growth. Even before the skin is formed, the basic pattern of our prints is created on the growing tips of the fingers and toes.

The patterns and proportions of the fingers are linked

But fingerprints and growth are not only genetically closely linked – there are also measurable correlations to the proportions of the fingers, as the researchers found. For example, people with a vortex pattern on their fingertips usually also have longer end links of the middle and ring fingers. This relationship is even clearer with the little finger: “People with a vortex pattern on both little fingers have an average of 1.32 millimeters longer little fingers than people without a vortex,” said Li and his colleagues.

“This is another classic example of pleiotrophy – the phenomenon by which the same gene affects several different traits,” explains co-author Sijia Wang from the Shanghai Institute for Nutrition and Health. The genes that control the growth and proportions of the hands and fingers also shape the basic pattern of fingerprints. How exactly these genes work and why at the fingertips sometimes whirls, sometimes loops or arches, is still unclear. (Cell, 2022; doi: 10.1016/j.cell.2021.12.008)

Quelle: Cell Press

Reference-www.scinexx.de

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